Southern N.W.T. tent caterpillar invasion part of natural cycle

They're fuzzy and a bit creepy to some, but tent caterpillars are also a sure sign summer has arrived. 

This year, their numbers also appear to be on the rise in the southern Northwest Territories.

"It's really hard to say if we're dealing with an outbreak right now, but we're definitely dealing with increased population levels that we haven't seen for a while now," says Jakub Olesinski, an ecosystem forester for the territorial government.

Olesinski says the upswing in population is probably the part of a natural cycle, prompted by an early spring and relatively mild weather with no heavy frosts.

Part of his job is to track all kinds of pests in the territory, including tent caterpillars, by aerial survey. He says the last major outbreak was in the 1990's.

"These disturbances will be visible from the air," says Olesinski.

"Forest tent caterpillar will cause defoliation to aspen forest and that… has a very characteristic look for the trained eye. We map them from the air and report them."

Creep factor for some, but not a serious threat

Forest tent caterpillars, the kind that are being spotted in the South Slave, feed on Aspen leaves.  

Olesinski says even if the bug eats all the leaves off a tree, they grow back in 3 to 5 weeks.  It would take several years in a row of that kind of defoliation to do any damage to the tress.

Just how much of a population boom the caterpillars are having, won't be clear until July, when department does its aerial surveys.  

"Most of the time they are on endemic levels which is very health for the eco-system. We shouldn't be worried about it."

Even if it is an outbreak, Olesinski says it's all part of a natural cycle.

So why track them?

"From the ecological point of view, it is important to know how climate change is affecting our forest," Olesinski says. "The presence of certain pests is one of the signs we see so it is important to keep track of them just to know what the situation is."

Winnipeg is experiencing a tent caterpillar outbreak this year, and city officials have decided to spray them.  However, Olesinski says that's not a step the territory would take in the wild.

Part of an ecologically complex system

Olesinski says people who want to rid their gardens or the bush near their cabins from the critters may also want to weigh the role they play in the ecosystem.

"They can be a benefit for several species of birds and other species who will feed on them and even on other insects that would feed on them," he says. "They are a natural phenomenon."

However, he does have some tips for people who don't want to share their space with the fuzzy creatures and their sticky, wispy nests:

• Do the deed early in the morning, or in the evening, when the larvae are in the tent.
• Get them while they're still in the larval stage. That way you prevent them from developing into a moth that will lay more eggs.
• Prune the section of the tree that holds the nest, and then destroy it from there.

Olesinksi says it's also perfectly fine to leave the caterpillars to do their thing. 

"Keep in mind that they only have one generation per year, each female lays only a single egg mass, and they are native to North America. So insects, parasites, and natural predators like birds and rodents control a certain amount of this population."